The present invention relates to audio/video communication, and more particularly to an interactive multimedia system that delivers low cost, highly reliable and high quality full motion audio/video communication to a computer desktop.
Currently there are various electronic communication systems for printed material, there are conferencing and messaging capabilities in audio only systems, and there are crude audio/video communication capabilities. Such audio/video communication systems as currently exist include the Intel Pro-Share, PictureTel and C-Phone systems. These systems use a common network for both graphics/command and audio/video data. Although the C-Phone system claims to separate C-Phone traffic from other LAN traffic, it still uses a single network for both graphics/command and audio/video data.
In general different data types are involved in multimedia communication. They include machine-control information, data regarding stored media, text, graphics, photographic images, audio and video. The richness of the communication is the result of the simultaneous presentation of many data types with well-defined timing relationships. For example, a movie as a multimedia experience has audio, video and text, such as sub-titles. It is true that if the image quality is bad, it ruins the experience. However image quality is not everything: it is extremely annoying to view a foreign language movie with voice dubbing that does not match lips, or likewise sub-titles that are off in time with respect to the action.
The information content of multimedia communication per unit time, i.e., bandwidth, that the human senses reasonably consume varies over many orders of magnitude. In increasing order there is text, graphics, photographic images, audio and video. Bandwidth essentially determines the quality of each type of data, but bandwidth alone is not the whole issue. The different types of data must be received and presented to the user in well defined timing relationships. More precisely they must be isochronous in time to the extent required by the particular application.
What is desired is an interactive multimedia audio/video communication system that provides all of the desirable features of existing print, voice and video communication systems while providing up to broadcast quality video in real time.
Accordingly the present invention provides an interactive multimedia system that separates lower data rate data types, such as machine-control, information about the stored media, etc., from the higher data rate data types, such as audio and live video. A digital graphics system includes a network server that communicates over a lower data rate graphics/command network to a plurality of desktop viewing stations. The graphics/command network is also used by the network server to provide machine control commands to various hardware components of the multimedia system. A separate higher data rate audio/video network, controlled by the network server via the graphics/command network, includes a router for switching input video to different outputs. The router includes a video splitter that receives multiple video outputs from the router and returns a single composited video input to the router. Also a non-linear audio/video storage system is coupled to receive and store audio/video data from the router as well as to play back audio/video data through the router. A distribution hub is coupled between the router and the desktop viewing stations to convert and transfer audio/video signals between the stations and the router.
The objects, advantages and other novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.